Sewing machine



Aug. 19', 1930.

o. 1.. LAWSON SEWING uAcHn'm Filed Jan. 5; 1926 2 Sheets-Sheet 1 Aug.19, 1930. L. LAWSON SEWING MACHINE Patented Aug. 19, 1930 UNITED STATESPATENT OFFICE J OSCAR I4. LAWSON, OF LYNN, MASSACHUSETTS, ASSIGNOR TOUNITED SHOE MACHINERY CORPORATION, OF PATERSON, NEW JERSEY, ACORPORATION OFNEW JERSEY SEWING MACHINE Application filed. January 5,1926. Serial No. 79,453.

The present invention relates to sewing machines and more particularlyto a presser foot lifting mechanism adapted for use in a lockstitch hornsewing machine.

The object of the invention is to proyide a presser foot liftingmechanism of new and improved construction which will operate in anaccurate and reliable manner to lift the presser foot a uniform distanceduring each cycle of operations of the machine irrespective of thethickness of the work.

A further object of the invention is to provide a mechanism of thischaracter in which the parts are so constructed and arranged asco-prevent all possibility of lost motion or slipping.

lVith these objects in view the invention consists of the devices,combinations and arrangement of parts hereinafter described and 23claimed. While the invention is particu larly adapted for use in alockstitch horn sewing machine it is also capable of use in other typesof sewing machines.

The several features of the present inven- 33 tion and the advantagesattained thereby will be readily understood by those skilled in the artfrom the following description taken in connection with the accompanyingdrawings which illustrate the features of the invention 37 as embodiedin a lockstitch horn sewing machine, so much only of the machine beingindicated as is necessary to show the connection of the inventiontherewith.

In the drawings Figure 1 is a left eleva- 53 tion of the presser footlifting mechanism, Fig. 2 is a front elevation of the same, Fig. 3 is adetailed rear elevation of part of the presser foot lifting mechanismincluding the bell crank lever and its cam, Fig. 4 is a de- 47 tailedside elevation, and Fig. 5 is a detailed rear elevation of the wedgeadjusting mech-,

. has a corresponding groove 42 :for the-lower anlsm.

The lockstitch horn sewing machine therein illustrated includes astraight hook needle indicated at 6, a presser foot 8, a shuttle withits bracket 10, and a horn which serves as a work support as indicatedat 12.

The needle is fast to the lower end of the needle bar 14 which isconnected through 50 link 16 with one end of the lever 18, the other thelever which engages a cam groove 26 in the cam disk 28.

The presser foot lifting mechanism, which embodies the subj cot-matterof this invention,

comprises a lifting lever, pivoted directly in front of the presser footbar on the machine frame, a block secured to thepresser footbar and acam-actuated bellcrank lever to operate the lifting lever. A wedgeinserted between the lifting lever and the block provides a meansautomatically to adjust the lifting mechanism to raise the presser foota uniform distance irrespective of the thickness of the work. A bellcrank lever is mounted on the presser foot bar with'its lower armconnected to the wedge and its horizontal arm arranged to engage anabutment on the machine frame. During the downward stroke of the presserfoot the lever is turned about its pivot to withdraw the Wedge a greateror less distance depending on the fall of the presser foot. During thelifting operation the wedge thus positioned with relation to thethickness of the work is held in adjust!- ment by means of a pinch dogmounted on the rear end of the lifting lever. The lifting movement ofthe cam-actuated bell crank lever first causes the pinch dog to clampthe wedge and then turns the lifting lever about its pivot to raise thepresser foot.

Describing this presser foot lifting mechanism somewhat morespecifically with reference to the drawings, the presser foot bar 30 hasfastened thereto a block 32 which has on its under side a groove 34adapted to receive the upper edge of a wedge 36. A lifting lever 38mounted on the machine frame at 40 directly in front of 'thepresser footbar edge of the wedge. To hold the vwedgein position during the liftingoperation a pinch dog 44 is mounted on the rear end-of the liftinglever. The wedge is-adjusted in accordance with the thickness of thework to allow the lifting lever always to raise the presser foot auniform, distance by means of a bell crank lever 46 pivoted onthepresser foot bar at 48. On the lower arm of this lever is a pin whichruns in a vertical slot 52 formed in the wed The horizontal arm carriesa pin 54 whic projects over a ledge or abutment 56 adjustably mounted onthe machine frame by means of screws 57 projectingtthrough verticalslots 58 in the frame. A s rmg 59 acting on the pin tends to force theliorizontal arm of the lever downwardly.

As P Q er falls, the lever is turned aboutits pivot by'the engagement ofthe pin with the abutment to slide the wedge to the right. Durin theupward stroke of the presser foot, t e wedge is held in position by thepinch dog and the pin 54 is lifted off its abutment against-the pressureof the spring 59. A set screw 62 is provided to adjust the position ofthe ledge or abutment and thus determine the distance the presser footis to be raised above the work. A bell crank lever 64 voted at 66 on'themachine frame carries omits vertical arm a roll 68 adapted to run on thecam surface 70. The other arm is adapted to engage the pinch dog pivotedon the litting lever. The lever 64 engages the pinch dog, first lockingthe wedge and then twt'hing the lifting lever about its pivot to raisethe prssser feet. In "order to permit an adjustment of the effectivethrow of the bell crank lever in its lifting movement the two arms arepivoted indzpendently at 66 and are held in the desired r atiorn to eachother by means of set screws 72.

The nature and object of the invention having been indicated and amachine embodying the several features of the invention havingbeendeacribed, what is claimed is INA sewing machine having, incombination, a work support, a presse/r foot, a presser foot bar, anabutment on the bar, a lift ng member, a w interposed between theliftingiiie'mber an the abutment, means for acmating the lifting memberto the presser and means for positioning the wedge with relation to thelifting member in aceel-dame the thickness of the work to raise theresser foot a uniform distance from the work to permit the feeding ofthe Wm. I i n I I 2. A sewing machine having, in combination, I worksupport, a preaserfoot, a presser feet bar, a 1i member, an abutment onthe resser foot alga wedge, a bell crank lever for ositiening the wedgepivoted on the ot her and having one end eonwith the wedge, and anabutment on time to engage the other end of at one end a pin and slotconnection with the wedge, and an abutment on the machine frame toengage the other end of the bell crank.

4. A sewing machine having, in combination, a work support, a presserfoot, a presser foot bar, means comprising an adjustable wedge and alifting member to raise the presser foot a uniform distance irrespectiveof the thickness ofthe work, means for positioning the wedge inaccordance with the thickness of the work and a pinch dog to lock thewedge in position during the lifting operation.

5. A sewing machine having, in combination, a work support, a presserfoot, a presser foot bar, an abutment on the presser foot bar, a liftinglever, an adjustable Wedge supported on the lifting lever and arrangedto come in contact with the abutment, a pinch dog pivoted on the liftinglever to lock the wedge in position, and means operating on the pinchdog to lock the wedge in position and thereafter actuate the liftinglever to raise the presser foot.

6. A sewing machine having, in combination, a work support, a presserfoot, a presser foot bar, a block fixed to the bar, a lifting lever, 21wedge arranged to cooperate with the lifting lever and the block to liftthe presscr foot, means for positioning the wedge to raise the presserfoot a uniform distance regardless of the thickness of the work, a pinchdog to lock the wedge in position during the lifting operation, andmeans to operate the pinch dog to lock the wedge and thereafter actuatethe lifting lever to raise the presser foot.

7. A sewing machine having, in combination, a work support, a pressei'foot, a pressei' foot bar, means comprising an adjustable wedge and alifting member to raise the presser foot a uniform distance irrespectiveof the thickness of the work, a pinch dog to lock the wedge in positionduring the lifting operation, a cam, and a lever actuated by the cam tooperate the pinch dog to clamp the wedge in position and thereafter toactuate the lifting member to raise the presser foot.

8. A sewing machine having, in combination, a Work support, a prcsserfoot, a presser foot bar, a block fixed to the bar, a lifting lever, anadjustable wedge supported on the lifting lever and arranged to come incontact with the block, a pinch dog pivoted on the lifting lever to lockthe wedge in position, a cam and a bell crank lever actuated by the camto operate the pinch dog to clamp the wedge in position and thereafterto actuate the lifting member to raise the presser foot.

In testimony whereof I have signedmy name to this specification.

OSCAR Lawson.-

